A novel technology will improve OLED devices

The organic light emitting diodes (OLEDs) is one of the types of display technology that is used in developing of digital displays for various devices such as TV screens, computer monitors, smartphones, digital cameras and etc. This technology has some limitations such as low electrical conductivity. Therefore, scientists from Korea developed innovative flexible transparent electrodes with Ag fibers, which are at 100 times longer than Ag nanowires. This invention significantly improves the electrical conductivity and transparency of OLED displays.

The novel technology was developed by the scientific group, led by Professor Byeong-Kwon Ju, from the Korea University in collaboration with Professor Young Wook Park from the Sun Moon University.

OLEDs have the unique properties of lightweight, flexible, transparent and color tuneability, which makes them an ideal modern light source. Interest in OLEDs is explained by the manifold benefits presented by this technology: operation in emissive mode (doesn't need backlighting), a wide viewing angle, a low operating voltage, light emission throughout the visible, flexible displays and cost-effective production. Ag nanowires consist of thin wires Ag, which diameter is 1 nanometer. Comparing to current transparent electrodes (ITO), Ag nanowires provide the hight flexibility, electrical conductivity, and transparency. They are considered as an ideal material for display' transparent and lighting devices. Despite this fact, Ag nanowires are difficult to utilize in OLED displays production as that have several limitations such as the length (1 micrometer), this, in turn, creates a barrier to enhance conductivity and transparency. Furthermore, increasing the roughness of the surface due to threaded connections also leads to electrical instability.

Scientists used the method of electrospinning, which applies polymer solutions for fibers production, to make junction-free Ag fiber electrodes of a few centimeters in scale. This process eases surface roughness control that is crucial for electrodes transparent and has the ability to prevent electrical instability of the OLEDs. In other words, it highly improves transparency, stability, and conductivity of such displays. The transmittance and resistance of Ag fiber electrodes can be independently regulated by controlling spinning time and Ag deposition thickness. They demonstrate the transmittance of 91.8% at a sheet resistance of 22.3 Ω-1. It causes the highest efficiency of OLED. Scientists mentioned that this novel technology will significantly improve different displays, wearable electronics, and lightening equipment.